Colorimeter.



PATENTED JAN. 8, 1907.

G. H. WHITE.

GOLORIMBTER.

APPLICATION FILED JUNE4.1906.

2 SHEETS-SHEET 1.

l/W TAIL-5.955

' CHARLES HENRY wnrrnor CAMBRIDGE, MASSACHUSETTS;

COLORIMETEHR.

Specification of Letters Patent.

Patented Jan. 8. 1907.

Application filed \Iun'e 4.1906. Serial No. 320,194.

To all whom it may concern:

Be it known that I, CHARLES- HENRY WHITE, a citizen of the United States, residing at Cambridge, in the county of Middlesex and "Commonwealth of Massachusetts, have invented certain new and useful Im rovements in Colorimeters, of which the fol owing is a specification.

This invention relates to a device for determinating the amount of a substance in a material by a color comparison. In making comparisons of this sort it is necessary'to have a color standard with, which the material to be investigated canbe compared, and this is usually done by preparing a standard solution of a known percentage and bringing the material to be tested to the same color by diluting one or the other or by similar steps.

. In order to make a comparison in this maneye in a convenient manner for comparison.

The determination of the percentage of carbon in steel is advantageously made by a color comparison, and thecolorimeter herein described is particularly more adapted for this test. In the specification which follows I have therefore described my colorimeter with particular reference to the testing of the amount of carbon in steel.

In the specification and the drawings which form a part thereof like letters of reference indicate corresponding parts through-' out.

In the drawings, Figure 1 is a front view of my colorimeter; Fig. 2, a vertical crosssection on the line 2 2 of Fig. 1 Figz. 3, a 1g plan section on the line, 3 3 of Fig. 2; a rear elevation with the casing removed; Fig. 5, a diagram of the color-image, and Fig. 6 a detail of one of the wedges.

A is an suitable base on which is mounted a frame upon which the mechanism of the device is located.

B is a box which forms a casing for the mechanism and which is hin ed to the base of the frame B and held in p ace by a catch 1). The box B has an o ening N through which the light enters. 8 is a corresponding opening in the frame B of adjustable width, and B re resents vertical slots in the frame I3, siitab fy spaced on each side of the opening O represents a pair of independent frames slidably mounted upon B and operated by racks E, which are engaged by pinions F, held on the frame B and rotated by the milled wheels G. The frames C and the racks E are connected through the slots B with the scales C, which are suitably marked -toread from the pointers P, marked on the face of B.

1) represents hollow wedges which may advantageously be made'by cementing together suitably-shaped pieces of glass with Canada balsam, or they may be held in any sort of a frame or otherwise fastened together. sides to exclude li ht. One wedge is slidably mounted on its ame C and adjusted by means of the screw d. The angle of these wedges is preferably small, and I therefore make the wedge" in the truncated form shown in Fig. 6 .to prevent undue length. Since a longitudinal vertical section of one of these wedges is triangular and equal in all respects to a similar section of the other wedge, it is not necessary to measure the thickness of the solution to determine the ratio, as the lengths of'each wedge from its end to the oint to be compared will give the same resu t. The scales 0 may therefore be any similarly-divided linear scales reading the length of the wedges-D. H is an assembling-reflector mounted over the opening 0 and covered by a slide H, which carries an eye-tube T, through which the o erator makes his observation. The assemb in -refiector H contains two reflectin mirrors and M placed at an angle Wit the opening 0 and similarly faced.

M is an oppositely-faced mirror set at an an gle to reflect from the mirrors M and M in the eye-tube T.

S is a section on the mirror M from which the back has been removed, so as to allow part of the light from the mirror M to pass through the mirror M and fall upon the mirror M Referring to the diagram in Fig. 3, it will be seen that the light passing through one The wedges are blackened on their the so ution in theleft-hand wedge.

wedge will fall-upon the mirror M, will pass through the openings of the mirror M and be reflected as a narrow band from the mirror M The light from the other wedge. will fall upon the IIIJI'IOI M and will be reflected over its entire surface with the exception of that art of the light which falls upon the surface ,i'roin which the backi has been removed. The mirror M will there ore reflect the light from'the mirror M in two blocks, and the transmitted li- 'ht from the two wedges will thereforebe resented to the eye of the observer witht e light of one wedge arran 'ed on two sides of a band of light from the ot er wedge and will appear as the image X. (Shown in Fig. 5.) This gives the observer an op ortunity to observe the transmitted light om the two wedges and to compare the colors of the same most advantageously. The slide H can be moved across the box H and the eye-tube T removed, if it is desired to pack an instrument in a small case.

In making a test the device is used as follows: A standard solution is prepared by dissolving steel of a known percenta; -e of carbon in nitric acid, and the solution is placedin one of the wedgessay the right-hand wedge of the device. The thickness of the solution will therefore vary with the thickness of the wedge, and by adjusting the wedge to vary the thickness the. standard may be presented in any strength desired. If, now, an equal portion of steel be dissolved in an equal portion of acid and placed in the other wed e, and the wedge moved until the color of the transmitted li ht is the same as that transmitted through the standard solution in the right-hand wedge, the scale will show in units the relative amount of carbon in the wedge. The percentage of carbon varies inversely in proportion to the thickness of the wed, e, and lnasmuch as the standard solution is known the reading of the scale of the wedge containing the solution to be tested will show by inverse roportion the percentage of 081%)01'1 in setting the left-hand wedge containing theiolution to be tested at the unit reading of the scale corres ending; to the known percentage of the stan ard solution and by moving the right-hand wedge containing the standard solution until the colors match, the reading of the scale of the standard wedge will give directly the reading in units corresponding to the percent. of the solution to be tested. For example, suppose a 0.30-per-cent. standard is use The left-hand wedge containing thesolution to be tested is set at 30. Suppose, now, after moving the right-hand wedge containing the known solution until the colors match the scale on the ri 'ht-hand wedge reads 36. I It will then be known at once and without computation that the percentage of the unknown solution inthe left-hand wedge is 0.36 per cent.

Various modifications in the liquid-holding means, adjusting mechanism, and means for comparing the colors may obviously be made without departing from the spirit of my invention.

What I therefore claim, and desire to secure by Letters Patent, is

1. In a device of the class described the combination of means for transmitting light, a plurality of li;i -ht-transmitti tanks for maintaining in bodies of liqui the same gradually-increasing thickness, and means to move said tanks inde endently across the path of the transmitte light.

2. In a device of the class described the combination of means for transmitti light, a plurality of lig -ht-transmitting tan rs for maintaining in bodies of liquid the same gradually increasing; thickness, means to move said tanks independently across the path of'the transmitted light and means to compare the interposed thicknesses of the Iiquidsin the tanks.

3. In a device of the class described the combination of means for transmitting li -ht, 

